Alternating-current magnet.



W. 8. SMITH.

ALTERNATING CURRENT MAGNET.

APPLICATION FILED SEPT. 10. I915.

Patented Apr. 17, 1917.

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ALTERNA'HNG CURRENT MAGNET.

APPLICATION FILED SEPT-10 IQIS- 1,222,900. Patented Apr. 17, 1917.

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WILLI AM S. SMITH, GF CATLZBRIDGE, MASSACHUSETTS.

ALTERNATING-CURBENT MAGNET.

Specification of Letters Eatent.

lPatented Apr. 1'7, 1917.

Application filed September 10, 1915. Serial 11019354.

To all whom it may concern:

Be it known that I, l VILLIAM S. SMITH, a citizen of the United States, residing at Cambridge, in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvement in Alternating- Current Magnets, of which the following is a specification, reference being had therein. to the accompanying drawings.-

This invention relates to an alternating current magnet.

Heretofore it has been customary in magnets of this character,:to make the magnet frame and core in laminatedsections; that is. thin metallic plates bound together, in order to prevent the excessive heating which the high magnetic density of a solid frame and a solid core entails. This construction is expensive and ismechanically poor. The laminations are apt to become loosened causing the magnet to become noisy and hum. VJ hen so made the cores are generally square or rectangular in cross-section and it is necessary to provide angular corner pieces as guides to their movements. This construction, however, renders smoothbearing surfaces impracticable so that the magnet is generally noisy in operation. The use of tubes of non-conducting material as bearings for the cores have been contemplated but such tubes soon become warped and get out of shape and moreover do not form good bearing surfaces for the cores.

The main object of my invention is to-provide an alternating current magnet which is quiet in operation and to this end I provide a guide tube forfthev core which is so constructed that the heating due to eddy currents, is practicallyeradicated.

A further object of my invention is to provide means whereby themovement of the core may be regulated to a fine degree in order to reduce the noise of operation of the the same; Fig. 3 is a central vertical'sectional view of the magnet; Fig. 4- is a front el ration of the same; Fig. 5 is a horizontal sectional view on line 55 in Fig. 3; Fig. 6 is an end view of the core; Fig. 7 is a side elevation of the core looking from left to right in Fig.6 Fig. 8' is a side elevation of the same turned ninety degrees from Fig. 7; Fig. 9 is a plan view of the core bracket; Fig. 10 is a side elevation of the core bracket; Fig. 11 is a side elevation'of the same turning Fig. 10 ninety degrees; Fig. 12 is a front elevation of the movable arm carrying the contact plates; Fig. 13 is a side elevation of the same; Fig. 1 1 is a side elevation of the toggle joint; Fig. 15 is a side elevation of the otl er toggle joint; Fig. 16 is a plan view of the other toggle joint and Fig. 17 is aside elevation of a stationary contact piece.

In the drawings illustrating one application of my invention is shown a two pole circuit closer or contactor in which 20 is a supporting base of insulating material upon which is mounted the magnet comprising a magnet frame 21, a coil 22 and a core 23 mounted within a guide tube 24. The magnet circuit is designated 25. I

In'order to prevent eddy currents and consequentheating while retaining a solid construction, the frame 21 is split from the center to the rear so as to form two wings 26 and 27, each of which is provided with a vertical extension 28 bored at 29 to receive a bolt 30 by means of which the magnet frame is attached to the supporting base 20. (See Figs. 35.) The space separating the two wings is shown in the drawings at 31 and this space suffices to prevent the circulation of eddy currents. The frame may be made in any suitable shape or form so long as this feature is retained.

In the core I prefer to retain the old construction of laminated sections 32 bound together by bolts 33 (see Figs. 6, 7 and S) but the core is substantially circular in cross-section except where flattened on two sides to permit the bolts to be headed. Secured to the magnet frame and within the coil is arranged the guide tube 24 in one piece but provided with a longitudinal slot 3 1. The tube and core are of such relative dimensions that the core fits the tube closely to avoid vibration and yet not so closely as to develop friction to retard the longitudinal movement of the core in the tube when the magnet is energized or deenergized. The guide tube and frame are so arranged that the slot 3a in the guide tube is in alinement with the space 31 between the two wings of the frame.

The core 23 is fixedly mounted in a bracket (see Figs. 911) having a collar portion 35 and two downwardly projecting lugs 36 each having a hole 37 to receive a belt or pin whereby the bracket may be connected to arms or levers to be operated by the movement of the core. The lower portion of the frame 21 is provided with a depending extension 38 having a recess 39 adapted to receive the bracket 35 the innersurface l0 of said recess forming a bearing surface for the bracket and also serving as a guide for the same. (Fig.

In the top of the magnet frame and ex tending into the top of the guide tube 2a is an adjusting screw ll held in any adjusted position by a set-nut 4-3. This screw limits the upward movement of the core when the magnet is energized. (See Fig. 3.)

Although the magnet is susceptible of various uses it is illustrated as operating a two pole circuit closer or contactor. Fulcrumed at on the frame is a yoke lever L6 (Figs. 12 and 13) its upper ends each carrying a contact piece 47 connected in a circuit as and insulated from the yoke lever by non-conducting material 49. The lower end of the yoke lever is connected to the core bracket by a toggle joint lever made up of two links 50, (Fig. 14:) and 51 (Figs. 16 and 17). The latter is pivotally mounted on the lower portion of the frame at 52 and I its free end is provided with a slot 53 through which passes a pin 54: mounted in the lugs 36 of the core bracket. The link connects the lower end of the yoke lever with the link 51. The outward movement of the yoke lever is limited by a rubber stop 55 on the frame extension 38.

Cooperating with the movable contacts 47 on the yoke lever 46 are fixed contacts 56 each mounted on a support 57. (See Fig. 17.) .For the purpose of securing a good fiat contact between each pair of contact pieces when operative, the contact 56 may be mounted on a plate 58 which is loosely mounted on two pins 59 carried by a plate 60 on the supporting member 57. Cotter pins 61 hold the plate 58 on the pins 59 and two helical springs 62 one on each pin 59 serves to keep the plate 58 and contact member 56 in a forward position at all times. This construction permits of a limited move ment of the contact member in all directions and has the effect of a universal joint.

The operation of the magnet is as follows. The magnet circuit 25 is controlled by any suitable form of switch not shown. When the switch is open, the magnet circuit 25 is open and the magnet is deenergized and the parts are in the position shown in Figs. 1, 2 and The closing of the magnet circuit, however, energizes the magnet thereby causing the core to be drawn upwardly until it reaches the end of its movement.

As the core is drawn upwardly the lower end of the yoke lever is thrown outwardly through the medium of the links 50 and 51 thereby causing the upper end of the yoke lever to be thrown inwardly and the contacts 17 to engage the contacts 56 and to close the circuit 48 which may be either direct or alternating. By having the stationary contacts 56 mounted on springs I secure :1 limited pivotal movement of the same which insures a full contact; that is. the contact "17 engages the Contact 56 on its entire face. At the same time the swings 62 permit the screw -11; to be adjusted to limit the move ment of the core in the magnet without affecting the contact. So long as the magnet circuit is closed the magnet remains energized and retains the yoke lever in the position of closing the circuit 1-8. \Vhen, however, the in guet circuit is broken and the magnet dei nergized, the core drops by force of gravity thus causing the upper end of the yoke lever to more outwardly and to break the circuit 48. The compression of the springs 62 assists this movement by forcing the upper end of the yoke lever outwardly.

In the operation of the magnet the arrangement of the two links 50 and 51 is an important feature. The link 51 is pivotally connected to the magnet frame at 52, which is a fixed point and is pivotally connected to the link 50 at which is a movable point. The other end of the link 50 is connected to tne yoke lever 4E6 at point 71 which is also a movable point. In Fig. 2, which shows the core 23 in its lowest position, the point 70 is below the points 71 and 52. When the magnet is energized the core is lrawn upwardly, which raises the point 7 0 throwing the point 71 outwardly and, to a slight degree lowers it, the point 52 remaining fixed. When the magnet is deenergized the force of gravity causes the core to drop and the springs 62 assist in this action by pressing the upper portion of the yoke lever outwardly. If the movement of the core 23 is great enough to raise the point 70, when the magnet is energized, into or above the horizontal plane in which the points 71 and 52 lie, then it will be apparent that as soon as the magnet is deenergized the action of the force of gravity upon the core may not be suflicient to cause it to drop and the core may remain in its upper position and the circuit 48 remain closed. It is important, therefore, that the point 70 should, when the magnet is energized, be below the horizontal plane passing through the points 71 and 52 and in order to reduce the noise of operation to a minimum, this point should be capable of fine adjustment. If the point 7 O is too far below the points 71 and 52 when the mag net is energized a loud humming noise will ensue, due to the fact that as the current in the circuit 25 fluctuates the core drops when the current weakens and is drawn back as the current increases in strength. These fluctuations being extremely rapid result in a vibration of the core and produce a humming noise.

It is important, therefore, that the movement of the core should be subject to control to a fine degree and the adjustment screw 4.1, which is one of the most important features of this invention, enables me to accomplish this result. By turning it to the right or left I can decrease or increase the length of the movement of the core and I have found from actual experience that I can almost entirely eradicate the humming noise by making proper adjustments of this screw. Further, if there is a slight variation between different magnets I have found that these variations can be overcome by making proper adjustments of the screw a1.

By constructing the magnet frame with the slot 31, in order to break up eddy currents and to prevent consequent heating of the frame, I am thereby enabled to use a. solid construction whereas heretofore it has been customary to make the frame in laminated sections. The solid construction can be made at a very much reduced cost, is permanent, does not become loosened by vibration or wear and enables perfect bearing" surfaces for the core and for the core bracket to be secured and, at the same time, permits the guide tube to be tightly fitted in the frame. Again, the frame being of solid construction may be larger in cross-section in order to reduce the magnetic density.

Another important feature of my inven tion resides in the slotted guide tube for the core. Heretofore, so far as I am aware, it has been impossible to use a metal guide tube for the core because of the excessive ieating, due to eddy currents, which affected the magnet coil and caused rapid deterioration of the magnet coil. By employing a metallic guide tube which is not subject to excessive heating, I am enabled to secure a smooth bearing surface in which the core may be well fitted in order to avoid vibration and noise. This also enables me to turn the core in a lathe and reduces the cost of construction.

Although I have shown my invention as applied to one particular use, namely, in a two pole circuit closer, it may be applied to various other uses to which a magnet of this character can be adapted. It is further to be observed that my invention may be embodied in other forms of construction than that herein shown and described and I desire to claim it broadly except where specifically limited in the following claims.

What I claim is 1. An alternating current magnet comprising a coil, a core, adjustable means forming part of the magnetic circuit for limiting the movement of the core when energized and means whereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

2. An alternating current magnet comprising a coil, a core, adjustable means adapted when said core is energized to be in magnetic seal therewith and to limit its movement and means whereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

3. An alternating current magnet comprising a coil, a core, adjustable means for limiting the movement of the core when energized and for regulating the length of the air gap when said core is not energized and means wnereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

4.. in alternating current magnet comprising a coil, a core, adjustable means for regulating simultaneously the movement of the core when energized and the length of the air gap when the core is not energized and means whereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

5. An alternating current magnet comprising a coil, a core, an adjustable screw forming part of the magnetic circuit for limiting the movement of the core when energized and means whereby the adjustment of said adjustable means regulates the. amount of pull of the load upon said core.

6. An alternating current magnet comprising a coil, a core, an adjustable screw adapted when said core is energized to be in magnetic seal therewith and to limit its movement and means whereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

7. An alternating current magnet comprising a coil, a core, an adjustable screw for limiting the movement of the core when energized and for regulating the length of the air gap when said core is not energized and means whereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

8. An alternating current magnet comprising a coil, a core, an adjustable screw for regulating simultaneously the movement of the core when energized and the length of the air gap when the core is not energized and means whereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

9. An alternating current magnet comprising a coil, a core, an operating member i connected to said core and adapted to be moved thereby when said core is energized, means in magnetic circuit with said core and sealed thereto when said core is energized, said means being adjustable in order to prevent the breaking of said seal between the impulses of the current exciting said magnet and means whereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

10. An alternating current magnet comprising a coil, a core, means connecting said core with its load, said means being so constructed that the pull on said core due to its load varies with the position of said core and means constituting part of the magnetic circuit for regulating the movement of the core when energized; said means being adjustable so that the movement of the core due to its load between the impulses of the current exciting the magnet may be regulated.

11. An alternating current magnet comprising a coil, a core, means connecting said core with its load, said means being so constructed that the pull on said core due to its load varies with the position of said core and adjustable means whereby the movement of the core due to said load between the impulses of the current exciting the magnet may be regulated.

12. An alternating current magnet com prising a coil, a core, adjustable means for regulating the amount of movement of the core when the magnet is energized and means whereby the adjustment of said adjustable means regulates the amount of pull of the load upon said core.

13. An alternating current magnet com prising a coil, a core, adjustable means for regulating the amount of movement of the core when the magnet is energized and positive means for returning the core to its normal position when the magnet is deenergized.

14. An alternating current magnet comprising a coil, a core, adjustable means for regulating the amount of movement of the core when the magnet is energized, means whereby the adjustment of said adjustable means regulates the amount of pull oi? the load upon said core and positive means for returning the core to its normal position when the magnet is deenergized. y

In testimony whereof, I hereunto set my hand in the presence of two subscribing wituesses, this the nineteenth day of August,

WILLIAM S. SMITH. Vitnesses F. J. V. DAKIN, RICHARD \V. I'IALL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of latents, Washington, D. 0. 

